Surface Ozone and its Precursor Gases Concentrations during COVID-19 Lockdown and Pre-Lockdown Periods in Hyderabad City, India

Drastic measures such as lockdown imposed in the countries worldwide to control the extent of COVID-19 have influenced environmental parameters substantially. The aim of the present study was to investigate the impact of lockdown on the air quality in Hyderabad city by comparing the pollutants concentration during lockdown and pre-lockdown periods. A comparative study was also made on the pollutant concentrations observed during the pre-lockdown (1st February – 23rd March 2020) and lockdown period (24th March - 30th April 2020) to those of the pollutants in the previous years (2018 and 2019). The Pearson correlation coefficient was employed to correlate the ozone (O(3)) concentration with other pollutants. Carbon monoxide (CO), nitrogen oxides (NO(X)) and O(3) were monitored along with meteorological parameters like temperature, relative humidity and solar radiation. It was observed that the O(3) concentration increased from 26 ppb (by volume) to 56.4 ppb during pre-lockdown and lockdown period, respectively, due to the decrease in CO and NO(X) concentration. The concentration of NO(2,) NO and CO were also reduced during the lockdown period by 33.7%, 53.8% and 27.25%, respectively. To identify the statistical significance of the parameters, analysis of variance (ANOVA) was used. The present study provides new insights on the ambient air pollution in terms of the aforesaid parameters and could pave the way for regulatory authorities to implement control measures to curb the air pollution. Highlights • COVID-19 lockdown improved the air quality by the reduction in air pollutants leading to increased ozone concentration. • Pearson model was used to correlate the ozone (O(3)) with oxides of nitrogen (NO(X)), CO and other meteorological parameters. • NO(X) and carbon monoxide (CO) concentrations were reduced by 33.7 % and 27.25 %, respectively, due to COVID lockdown. GRAPHICAL ABSTRACT: [Image: see text]